Green Wheel is a smart mobility system that collects energy while riding the bicycle and that releases it when needed. What if the same mechanism is used in the opposite way to control the speed and maximum distance from a trip guide? In this scenario, a grandfather brings around his grandkid for a Sunday trip in the park. In order to avoid potential risks, he sets a maximum distance range. Each time his grandkid goes beyond it, the system sends an alert and offers the possibility to decelerate the speed of the kid's bicycle.